Maybe you can "codify" the information. Just don't write the information a full text but as strange codes. Then they don't know what they modify anyway and you can write this information in a hidden question and you let people pass on only with a correct code.

So if you have a code like pqe0810KLS93841 for department 1, then no one will guess what department 2 is and fiddling with the code will most probably lead to a wrong code, so you can prevent them to go on by a condition.

Some notes: When passing the course to rate by URL you can additionally pass some cryptic number like "0c4000cdnber3" as second argument and then extend your condition to not only check on the course type/name but also check the fake ID number which you can hardcode for every course.